The invention relates to a method for folding a gas bag of a side gas bag. The gas bag is intended to be folded into a packet form which consists of a substantially rectangular fabric section rounded at the corners, which is folded along a common fold edge to an approximately square shape and the free edges of which, placed one over another, are connected with each other to form a closed gas bag, and in which in the region of the common fold edge a connecting plate for a gas generator can be arranged, the connecting plate having fastening bolts projecting outwards through the fabric.
The packet form of an gas bag for an gas bag module is determined on the one hand by the available installation space and on the other hand by the desired expansion behavior of the gas bag on being inflated explosion-like in an accident situation. In the case of so-called side gas bags, which are intended to reduce the risk of injury to the vehicle occupants with acceleration forces directed transversely to the longitudinal axis of the vehicle, the designer has to manage on the one hand with relatively small installation spaces and on the other hand must realize very short inflation times which lie in the region of only 20 to 30% of the inflation times which are available for front gas bags. Packet forms which satisfy these requirements must in addition be able to be realized as economically as possible.
For a packet form which fulfills all the above-mentioned conditions, it is proposed to fold an gas bag in the following manner: The gas bag consists of a substantially rectangular fabric section having rounded corners, the fabric section being folded along a first fold edge to an approximately square shape with free edges, the free edges being arranged one over the other and being connected with each other so as to form the closed gas bag, the gas bag being provided with a connecting plate adapted for connection to a gas generator and arranged in the region of the first fold edge, the connecting plate having fastening bolts projecting outwards through the fabric section. The method comprises the following steps: First, an edge of the gas bag running approximately perpendicularly to the first fold edge and belonging to a of the gas bag not containing the connecting plate, is turned into the gas bag so as to be arranged in parallel and adjacent to an opposite edge of the gas bag, whereby a fold form is produced which is four layered substantially throughout, extends parallel to the connecting plate and is comprised of two fabric section halves. Then, the fabric section halves are folded in parallel to the first fold edge to a fold form in which the connecting plate lies immediately adjacent to a second fold edge on a rim side, the fabric section having edges lying opposite the fold edge and being arranged adjacent to each other, the connecting plate and the fabric sections lying in planes parallel to each other. Thereafter, the fold form is turned down, by using a fold rule, through approximately 90xc2x0 from a plane parallel to the connecting plate along the first fold edge as well as along fold edges lying parallel to each other and spaced apart from the connecting plate and from each other, a free space being formed between every two adjacent layers of the fabric sections for the insertion of a fold rule. Then, the free space is widened by means of a fold rule and the remaining fabric material is then, by means of further fold rules externally engaging and inserted, folded in on both sides from a center of the free space several times in meandering form in layers parallel to the connecting plate. Finally, the packet form thus produced is turned down through 180xc2x0 around two fold edges running perpendicularly to each other, and is pressed on a reverse face against the gas bag region containing the connecting plate.
It has been found that in this way a packet form can be achieved in which the gas bag for a side gas bag can be folded to the available installation space without difficulties, without any unnecessary delays occurring during the explosion-like inflation, through which the prescribed short inflation time would be exceeded. The folding expenditure remains within the framework of conventional gas bag folding methods. As regards the arrangement of the connecting plate, both a symmetrical and also an asymmetrical position is able to be realized.